This invention relates to improved tubular remote controls of the type having a push-pull element slidable in a tubular sheath, and more particularly, to such controls in which a seal is provided around at least one end of the push-pull element.
Push-pull remote controls fall into two principal types: the wire or cable type and the ball bearing type. An old and familiar wire type control was the Bowden control used to operate the choke from the dashboard of early automobiles. A modern form of the cable type of remote control is shown in U.S. Pat. No. 3,994,185.
U.S. Pat. No. 3,452,615 is illustrative of the ball bearing type of remote control in which a push-pull blade is movable in a tubular sheath while supported by a series of spaced ball bearings disposed in contact with each of the two wider faces of the blade. U.S. Pat. No. 3,464,285 shows a similar remote control in which the movable blade or core is supported between two opposed series of quasi-cylindrical rollers in lieu of ball bearings.
When at least one end of a push-pull remote control is in a dusty or smoky atmosphere, foreign matter such as tar from tobacco smoke slowly infiltrates into the tubular sheath of the control between the end rod and the end fitting of the control. The accumulation of foreign matter in the control is accelerated when one end is exposed to a higher atmospheric pressure than the pressure prevailing at the other end of the control. For example, such a pressure unbalance is encountered in remote controls used on airplanes where one end of the control is within the pressurized body of the airplane and the other end is outside that body. In a period of time, the accumulation of foreign matter in the control can build up to a level which will make movement of the push-pull element difficult and, in some cases, even impossible. This tendency is particularly hazardous in the case of remote controls on airplanes. Even moisture entering a remote control is dangerous because of freezing.
Accordingly, the object of this invention is to provide a ring seal around at least one end rod and within the end fitting of a push-pull remote control to impede the infiltration of foreign matter into the control.